In this domain many types of luggage made of thermosetting or injectable plastics are known. The factor limiting the dimensions of suitcase of this character is the weight, both of the container and of the contents, for meeting the requirements imposed by the forwarding agent, for example by air, and those resulting from the user's capacity to easily move his suitcase between the departure point and the arrival point of public or private transport means.
When the size of a suitcase becomes relatively large so that its capacity meets the many impediments to be enclosed therein, the problem arises of its transfer to the transport means utilized, notably in railway stations or airports.
In countries where the travellers' comfort is taken into consideration, caddies are put at the public's disposal. There are also devices provided with detachable or fixed rollers, but in addition to their cumbersomeness and their weight, the convenience of their use is not always obvious.